Writing instrument



FIG. 1 is a front elevational view of a writing instrument showing my new design;

FIG. 2 is a right side view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a perspective view thereof; and,

FIG. 7 is a front elevational view thereof with the writing tip extended. 

The ornamental design for a writing instrument, as shown and described. 